Tunneling-shield.



No. 794.634. PATENTED JULY 1l, 1905l TUNNELING SHIELD.

APPLICATION FILED MAR. 18, 1905.

@www d W M N N m Wm m lIO UNITED STATES Patented July 11, 1905.

PATENT OFFICE.

ERNEST W. MOIR, OF LONDON, ENGLAND, ASSIGNOR TO S. PEARSON AND SON, INCORPORATED, OF LONG ISLAND CITY, NEW YORK, A CORPORA- TION OF NEW YORK.

TUNNELlNG-SHIELD.

SPECIFICATION forming part of Letters Patent No. 794,634, dated July 11, 1905.

Application filed March 18, 1905. Serial No. 250,785.

To rif/Z whom, t may concern:

Be it known that I, ERNEST W. Moin, a subf ject of the King of Great Britain and Ireland, residing' in London, England, have invented certain new and useful Improvements in Tunneling-Shields, of which the following is a specification. y

My invention relates to apparatus for the construction of tunnels, especially such as are intended to be carried through water-bearing strata and in which an advancing shield is employed as the excavation is advanced and the tunnel-lining is put in back of the shield, the operations being carried on under air-pressure greater than atmospheric pressure.

The object of my invention is to provide eiiicient means to prevent the inrush of water or escape of air between the iron tunnellining and the tail end of the shield.

In the accompanying drawings, Figure l is a diagram on a small scale indicatinga tunnel end and shield of suitable construction, and Eig. 2 is an enlarged longitudinal section through a part of the tail end of the shield and the forward segments of the tunnel-lining when provided with my improvement.

Referring to Fig. 1, A represents the shield, which has the usual forward cutting edge c and air-looks B B. The tunnel-lining, which preferably is built up of curved segments c, is represented at O, the annular tail end a of the shield being outside of and surrounding the forward end of the tunnel-lining. Hydraulic jacks D are mounted on the shield in such position that their piston-heads CZ can be brought to bear against the forward edges of the latest inserted segments c to force the shield forward at the proper time, as is wellunderstood in the art.

In using tunneling apparatus of the character described it is customary, especially in cutting through water-bearing strata, to employ compressed air in the working chambers, and it has always been a difficult problem to secure a tight joint between the tail end of the shield and the tunnel-lining, such a joint as will prevent, on the one hand, an inrush or iiow of water and, on the other hand, escape of compressed air. To meet this difiiculty, I provide the packing means which I will now describe.

I mount upon the inner face of the shield at a point where it overlaps the tunnel-lining an annular pipe P, with suitable supply and return pipes p running longitudinally of the shield and tunnel to points in advance of the forward edge of the lining and between the hydraulic jacks D. There the pipes p are provided each with a suitable connection p', to which can be connected up supply and return pipes from a freezing apparatus to circulate freezing brine through the pipe P.

After each advance of the shield clay or other suitable material in a moist state or capable of taking moisture is pugged into the space between the tail of the shield and the lining about the pipe P, as at fr, and then frozen by the circulation of the cold brine through the piping.

I claim as my invention- In combination with a tunnel-lining and advancing shield, means to freeze moist material pugged in the joint between the lining and shield.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ERNEST W. MOIR.

Witnesses:

C. SEDGwIoK, HUBERT HowsoN. 

